Using PAGE method, we analysed genomic RNA patterns of several standard strains of rotavirus including Wa, Ito, Yo Hochi, ST, SA-11 and UK strains, and the epidemic strains of rotavirus which caused infant diarrhoea in Nanjing in October to December 1989. It was interesting that the electrophoretic model of Wa strain had changed from 4:2:3:2 to 4:3:3:2, and then to 4:3:4:2 after it was cultured on MA104 or CV-1 cells for several passages. Three variants were cloned by the plaque assay from the "Wa" strain w...